The present invention relates to an ICP mass spectrometer.
Analytical problems in the field of ICP mass spectrometers demand devices which are inexpensive and have high detection limits. In this case small quantities of available test material, on the one hand, and a short measuring time or other reasons, can be behind the demand to supply the highest possible fraction of ions generated by inductively coupled plasma (ICP) to a useable detection.
DE 43 33 469 A1 describes an analytical device comprising an ICP ion source and a connected mass spectrometer of the Nier-Johnson type. In this case only a narrow measuring window can be simultaneously registered, wherein the respectively detected mass can be variably tuned in terms of time. The illustrated spectrometer extracts the ions from the ICP source by means of a separately pumped sampler-skimmer unit.
ICP mass spectrometers are also generally known in which ions from an ICP source can be transferred via a sampler-skimmer unit into a spectrometer of the Mattauch-Herzog type.
U.S. Pat. No. 6,107,628 describes a particle optical system under the term “ion funnel”, by means of which improved extraction of charged particles is possible from a region of high pressure between 0.1 mbar and 1 bar into a region of relatively low pressure, in particular a high-vacuum region. The ion funnel can either be constructed as a stack of washers with central apertures that decrease from the high-pressure side to the low-pressure side, wherein the washers are loaded with out-of-phase high frequency alternating voltage, or as a pair of coils, through which current flows, with decreasing diameter. The entire disclosure of U.S. Pat. No. 6,107,628 is hereby incorporated for the purpose of defining the term “ion funnel”. The term “ion funnel” also includes interim developments of an extraction optical system corresponding to the design of U.S. Pat. No. 6,107,628.